As well as having a tailored functionality, modern plastics are also intended to do increased justice to environmental concerns. As well as by a general optimization of preparation processes, this can be achieved through the use of greenhouse gases, such as carbon dioxide, as building blocks for synthesis. Accordingly, for example, a better environmental balance for the process can be obtained overall via the fixing of carbon dioxide. This path is being followed in the area of the production of polyethercarbonates, and has been a topic of the intense research for more than 40 years (e.g., Inoue et al, Copolymerization of Carbon Dioxide and Alkylenoxide with Organometallic Compounds; Die Makromolekulare Chemie 130, 210-220, 1969). In one possible preparation variant, polyethercarbonate polyols are obtained via a catalytic reaction of alkylene oxides and carbon dioxide in the presence of H-functional starter compounds (“starters”). A general reaction equation for this is given in scheme (I):

A further product, in this case unwanted byproduct, arising alongside the polyethercarbonate polyol is a cyclic carbonate (for example, R═CH3 propylene carbonate).
Various refinements of this process are known in the literature. Thus, for example, US 20100048935 A1 describes a process for preparing polyethercarbonate polyols in which alkylene oxides and carbon dioxides are added onto H-functional starter compounds using a DMC catalyst. Within the process, one or more starter compounds are introduced initially in a reactor, and then one or more starter compounds are metered in continuously to the ongoing reaction in the reactor.
WO 2006103213 A1, in contrast, describes a process for preparing polyethercarbonate polyols that features improved incorporation of CO2 into the polyethercarbonate polyol, using a catalyst containing a multimetal cyanide. The process discloses the presence of a H-functional starter, an alkylene oxide, and carbon dioxide in the presence of the multimetal cyanide component in a reactor. The process further discloses the presence of a CO2-philic substance or of CO2-philic substituents. The CO2-philic substance or the CO2-philic substituent is intended to increase the incorporation of CO2 into the polyethercarbonate polyol and so to reduce the formation of cyclic alkylene carbonates, such as propylene carbonate, for example, which represent unwanted byproducts.
WO 2010/028362 A1 discloses firstly polymerization systems for the copolymerization of CO2 and epoxides, comprising: 1) a catalyst with a metal-coordination compound having a permanent ligand set and at least one ligand which is a polymerization initiator, and 2) a chain transfer agent having two or more sites which are able to initiate polymerization. This patent application further discloses processes for the synthesis of polycarbonate polyols with the polymerization systems described therein. Disclosed lastly are polyethercarbonate polyol compositions which have a high percentage of OH end groups and a high percentage of carbonate groups. A further feature of the compositions is that they include polymer chains which a polyfunctional unit that is linked to a plurality of individual polycarbonate chains.
The publication “Synthesis of side-chain liquid crystalline polycarbonates with mesogenic groups having tails of different lengths” by John C. Jansen et al., Macromol. Chem. Phys. 200, 1407-1420 (1999) describes, in a model system, the terpolymerization of glycidyl phenyl ether, propylene oxide, and CO2. Catalysts used in this publication are organozinc catalysts.
EP 2 465 890 A1 relates to a process for preparing polyethercarbonate polyols having primary hydroxyl end groups, comprising the steps of reacting a starter compound containing active hydrogen atoms with an epoxide and with carbon dioxide under double metal cyanide catalysis, reacting the resulting product with a cyclic carboxylic anhydride, and reacting this resulting product with ethylene oxide in the presence of a catalyst which comprises at least one nitrogen atom per molecule, with the exception of noncyclic tertiary amines having identical substitution. The patent application further relates to polyethercarbonate polyols obtainable by this process, to compositions comprising these polyethercarbonate polyols, and to polyurethane polymers based on these polyethercarbonate polyols. Japanese patent application JP 50-154348 A relates to a thermosetting polycarbonate composition which is prepared from a polycarbonate having an aliphatic polycarbonate containing double bonds, from a crosslinking catalyst, and, optionally, from a radically polymerizable unsaturated compound. A copolymer of allyl glycidyl ether, carbon dioxide, and propylene oxide and also dicumyl peroxide are mixed in dioxane and dried under reduced pressure.
US 2011/0251355 A1 discloses the preparation of poly(alkylene carbonate) by alternating copolymerization of carbon dioxide and epoxides. Described specifically is the preparation of block copolymers or graft copolymers by alternating copolymerization of an epoxide and carbon dioxide with a metal(III)-salen complex, with a quaternary ammonium salt as catalyst.
Disadvantages of these process regimes presented, however, are that the reaction of the monomers is slow and the reaction products include polyethercarbonates which have a relatively high viscosity, causing them to have relatively poor further-processing properties. Thus, for example, the high viscosity limits the possibility for further reaction of these prior-art polyethercarbonates in further crosslinking reactions.